The overall intent of this project is to serologically characterize cell surface antigens associated with human leukemia by means of allogenic and xenogenic sera. The specificity of antisera for different leukemia cell types will be determined by combinations of cytotoxic and immunofluorescent assays against panels of leukemic and normal cells. Specific antisera will also be used to isolate and characterize purified human myeloblastic leukemia cell surface antigen (AMLSGA). The eventual availability of both highly specific antibody and a potent radioactively labelled antigen will allow development of a competitive binding radioimmunoassay for experimental use and possible clinical use.